I'm actually more intrigued by the caped, man in white. He has been rumored several times (and thought to be played by Mendelsohn). I imagine he might be some sort of high Imperial official and perhaps they've even decided to make Grand Admirals officially canon. Perhaps he'll be a Tarkin surrogate and "holding Vader's leash", with (CGI?) Tarkin himself relegated to a more limited role.
Or maybe that's not him?
http://makingstarwars.net/2016/02/m...t-the-bad-guy-in-rogue-one-a-star-wars-story/